Trudy Rubin: Joe Biden's foreign policy legacy goes through Ukraine

As the election nears and tension builds between Donald Trump and Kamala Harris, many people may have forgotten that Joe Biden is still president until January.

In that limited time, he can still shape a lasting foreign policy legacy — one that I believe will be defined by the outcome of the war in Ukraine. How Biden approaches that conflict at the end of his term will resonate far beyond the battlefield.

Moscow and Beijing (along with Tehran and Pyongyang) are watching closely to see whether the president finally gives Kyiv the key weapons systems it needs to win — and a green light to use them wherever needed. That would include permission to use U.S.-made long-range ATACMS missiles to destroy military bases inside Russia from which planes fire glide bombs that have decimated Ukraine's cities.

If Biden gives Ukraine this critical help, it will hedge against a possible Trump victory, since the former president has pledged to cut off aid if Kyiv doesn't bow to Vladimir Putin's version of "peace talks." If Biden holds back, however, it will signal to Putin and Xi Jinping that Washington doesn't have the will to stop territorial aggression and is intimidated by Putin's nuclear bluster.

It will also put Harris on a foreign policy backfoot if she takes over the White House.

Biden's decision may become clear this week when he meets with Ukrainian President Volodymyr Zelenskyy in New York City, where both will address the United Nations General Assembly. Zelenskyy will present his "victory plan" and spell out what Ukraine needs to beat back its invaders.

Zelenskyy believes Putin will only negotiate once he believes his war is unwinnable, which means Ukraine needs the weapons to convince him. And Kyiv has made clear it will only negotiate if the Russian leader is forced to adhere to the United Nations charter, which prohibits the use of force against the territorial integrity or political independence of any state. Again, weapons are key.

The issue of using ATACMS inside Russia has become central, since Ukraine has no other way to prevent the Russians from firing long-range glide bombs directly at its cities. The Ukrainian military wants to hit Russian aerodromes before the bombs are launched, but so far Biden has not given permission. Great Britain has given Ukraine the green light to use its Storm Shadow missiles inside Russia but prefers to act in tandem with Washington.

A big part of the problem is Putin's nuclear saber-rattling. He has blared that using ATACMS would be a declaration of war by NATO. He and his propagandists issue constant warnings about using nuclear weapons if Russia's sovereignty is threatened.

But unlike Moscow, Kyiv has never threatened the sovereignty of another country, only struck back against Putin's effort to destroy Ukrainian independence. As for fears of "escalation," it is Moscow that is escalating against Western democracies.

The Kremlin has just received short-range missiles from Tehran, and huge numbers of artillery shells from Pyongyang. In exchange, the United States believes Putin will help Tehran with nuclear weapons technology, which could advance Iran's nuclear threats to Israel and elsewhere. No one is certain what the Russian leader is providing to North Korea as payment.

But what is certain is that Putin is part of a tightening network of aggressive states hostile to the U.S., and helping arm Moscow either directly or indirectly, including China, North Korea, and Iran.

Moreover, Ukraine has repeatedly crossed Putin's red lines and nothing has happened, including the use of ATACMS against Russian bases in occupied Crimea, and the invasion of the Kursk region of Russia. The Kremlin's nukes appear more useful as a bogeyman than as a weapon whose use would backfire on it.

While Putin's nuclear bluster must be considered, the West shouldn't be unduly intimidated. If the West bowed to every such threat, Putin could blackmail NATO allies to do anything he wants.

What is deeply disturbing is to watch Trump echo Russian propaganda, warning about World War III if Biden gives Ukraine the weapons it needs. The reverse is far more likely: A Western failure to push Putin back from Ukraine is more likely to lead to World War III, as Putin and Xi conclude they can seize territory without paying a price. Think Taiwan.

When Robert F. Kennedy Jr. and Donald Trump Jr. write in an op-ed in the Hill that "no vital American interest is at stake" in Ukraine, they reveal how ignorant they — and Junior's dad — are of history. Think Neville Chamberlain's "peace for our time" deal with Adolf Hitler when the Nazi leader seized the Sudetenland region of Czechoslovakia.

As Zelenskyy told me in a June interview in Kyiv, "A cease-fire [with Ukraine] is the best option for the Russians so they can prepare for taking even more."

Yet, Putin's nuclear threats have repeatedly deterred Biden and NATO allies from providing Ukraine with vital systems when they were most needed. To protect its skies, Ukraine has been begging for Patriot air defense systems and F-16 fighter planes since the war started, yet only a tiny handful of each have arrived. The Europeans were willing to donate dozens of F-16s many months ago, but Washington denied them the green light until recently and delayed giving Ukrainian pilots priority slots for training.

Then there is the tragic shortage of artillery shells, promised months ago by the United States and Europe, that is enabling Russian forces to advance in eastern Ukraine. Some frontline towns I visited on a trip to Ukraine in June have already been captured. That's because, as I heard from Ukrainian troops, Russians have up to a 12-1 advantage in artillery shells in some areas.

Moreover, if ATACMS had been allowed months ago for use against Russian aerodromes, they could have prevented horrendous damage to Ukraine's cities. By now, Russia has moved most of its planes out of ATACMS range, but there are still plenty of key targets that could be destroyed.

"It is really difficult to hear the same answer every time: 'We are working on it,'" Zelenskyy told the Yalta European Strategy conference in Kyiv earlier this month. "Russian missiles and Iranian-supplied Shaheds unfortunately are also 'working' in our skies and against our people. And Putin doesn't need any permissions or approvals."

And yet, as I saw on my Ukraine trip, the country's fighters are brilliant innovators who have developed technological devices — such as sea drones that drove the Russian fleet out of the Black Sea — that have so far prevented Russia from major advances. Indeed, the U.S. military is taking lessons from Ukraine in technological warfare.

Still, to end this war, Ukraine needs Biden to instruct the Pentagon to treat Kyiv's war as if it were our war. A war not of conquest, but of forcing an aggressor to abide by the U.N. charter and international law.

The aim is not to destroy Russia, but to force Putin to the table on Ukraine's terms. By doing everything possible to fully arm Ukraine before he steps down, Biden can still give Ukrainians a fighting chance to overcome Putin's aggression — and push back against any Trump effort to sell them out to the Kremlin.

That would be a legacy Biden could be proud of — and upon which a President Harris could build.